textproduct: Quad Cities

KEY MESSAGES

- Very hot and humid weather will continue through the end of the week and into the weekend, with peak heat index values between 100-110, especially for areas along and south of Highway 30.

- Precipitation chances will remain limited for many, with best chances north of Interstate 80 through the end of the work week.

- Temperatures and humidity will trend upwards again through the middle of next week, resulting in heat indices nearing 100. A more active pattern may also take shape, leading to shower/storm chances and challenges in the temperature forecast.

SHORT TERM /THROUGH FRIDAY/

Issued at 158 PM CDT Thu Sep 3 2026

Upper ridge will continue to build over the Central CONUS through the end of the week, with upper level flow becoming more northwesterly. Once again, we will be dealing with a stalled- boundary north of the forecast area. This boundary may start to slowly sag south due to the retrograding ridge towards the Central CONUS, bringing the chance for showers/storms closer to our counties along Highway 20 in Iowa and parts of northwest Illinois. We can start to see this corridor of showers/storms approach these areas after midnight tonight, lasting into Friday morning (15-30% chances). With that in mind, maximum temperatures Friday are uncertain in our north, owing to the potential for active convection or decaying ovenight convection. Although, guidance still favors much of this activity staying north of our area or leaving a small imprint on our area. There also remains a low- end chance for a strong to severe storm, but the severe threat coverage would be isolated. Overall, we have a Marginal Risk for severe weather for areas along/north of Interstate 80. Although, PoPs remain well north of Interstate 80, thus limiting the threat for areas along the interstate.

Given uncertainty on the shower/storm chances, we believe we will have a better chance of having yet another very hot and humid day throughout the area. Thus, we opted to extend the current Heat Advisory for areas north of Highway 30 through Friday, as there will be the chance for heat indices around 100-105. Otherwise, a mix of clouds/sun will be seen, especially in our north, with a light southwesterly breeze.

LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/

Issued at 158 PM CDT Thu Sep 3 2026

This Weekend...

Ridge will remain situated over the Central CONUS, with the aforementioned boundary finally starting to move south. This will generally come through similar to a backdoor cold front, moving into our northeast and tracking southwest through much of northwest Illinois and eastern Iowa Saturday. This may leave the boundary draped over our area midday Saturday, which can be a focal point for diurnally-driven convection. There remains some uncertainty on coverage, with timing largely confined to the afternoon hours. Although, any decaying convection from Friday night and Saturday morning may also provide outflow boundaries for further shower/storm development. Overall forcing will remain weak, which should limit coverage to isolated-scattered. Areas along/south of Interstate 80 will continue to be of concern for very hot/humid conditions, where heat indices are expected to reach 100+ again. Thus, opted to extend most locations currently under the Extreme Heat Warning through Saturday. Areas north of the boundary will experience a less humid airmass with air coming from the Great Lakes Region.

Sunday will largely be under the influence of the post frontal airmass, with the boundary stalled out from northwest-southeast over Central Iowa. Being post-frontal, a much different airmass will be in place throughout. Temperatures will range from near 80 in northwest Illinois to upper 80s in southeast Iowa, with dewpoints largely in the 60s to low 70s. These conditions will result in heat indices finally below 100 throughout, with areas south of Interstate 80 seeing values in the low-mid 90s. While this is still unseasonably warm, the airmass will be more pleasant than we have seen over the last week for many.

Next Week...

Ridge over the Central CONUS will start to track easterly, flattening as it does. Although, it will be slow to break down, with increasing llvl south/southwest flow into the area resulting in increasing heat/humidity again. There will be the chance for upper 80s to low 90s once again, with dewpoints increasing into the low-mid 70s. Thus, heat index values will be on the rise as well, increasing to near 100 again. Midweek and beyond, we will generally fall under weak zonal flow. Upper level pattern would favor us falling under the path of passing shortwaves, favoring a potentially active pattern. Although, this is still a ways out in the forecast, leading to plenty of uncertainty. NBM would favor daily PoPs (20-40%) Tuesday onward, which could lead to temperature forecast challenges as well.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 640 PM CDT Thu Sep 3 2026

Light showers have dissipated early this evening across eastern Iowa with VFR conditions expected through the period. A disturbance passing to our north and east tonight could bring a period of SHRA and TSRA to DBQ between 9 and 14 UTC Friday as a line of storms moves southeastward across Wisconsin. Confidence is low in this occurring so placed a prob30 at DBQ for MVFR conditions during this time period. Light south winds are expected overnight with winds turning to the southwest after 12 UTC with speeds of 5 to 10 knots.

CLIMATE

Issued at 558 AM CDT Thu Sep 3 2026

The Quad Cities (MLI) has had two days to start this month with 95 degree highs. If a third happens today, it would be the longest such stretch in September since September 4-6, 1990.

Record Warm Low Temperatures:

September 3: KDBQ: 73/1939 KMLI: 76/1939

September 4: KDBQ: 71/1912 KMLI: 74/2018

September 5: KDBQ: 76/1881 KMLI: 76/1925

DVN WATCHES/WARNINGS/ADVISORIES

IA...Heat Advisory until 7 PM CDT Friday for IAZ040>042-051>054-066. Extreme Heat Warning until 7 PM CDT Saturday for IAZ063>065- 067-068-076>078-087>089-098-099. IL...Heat Advisory until 7 PM CDT Friday for ILZ001-002-007-009. Extreme Heat Warning until 7 PM CDT Saturday for ILZ015- 024>026-034-035. Extreme Heat Warning until 7 PM CDT Friday for ILZ016>018. MO...Extreme Heat Warning until 7 PM CDT Saturday for MOZ009-010.